Recycling nitrogen with water lettuce biochar: ammonium adsorption from industrial wastewater and application as soil conditioner
摘要
Over recent years, biochar has emerged as an effective adsorbent for ammonium (NH4+) from several wastewaters. However, the application of NH4+-loaded biochar to assist plant development has been neglected. This study investigated the efficiency of biochar in the adsorption of NH4+ present in wastewater of a metal pipe industry, and the use of NH4+-loaded biochar as a substrate conditioner to produce pepper seedlings (Schinus terebinthifolius). Biochar samples were prepared by pyrolysis of water lettuce (Pistia stratiotes) at 400, 500, and 600 °C and washed with 0.1 mol L−1 HNO3 until pH 7.0. The results showed a clear effect of pyrolysis temperature and/or acid washing on the ammonium uptake with a slight increase in NH4+ uptake for the biochar produced at 400 °C. Adsorption kinetics and isotherm data were satisfactorily described by the pseudo-second order kinetic model and the Langmuir isotherm model, respectively. The mixtures containing 2.5, 5.0, and 7.5% of NH4+-loaded biochar in the commercial substrate, resulted in high production of chlorophyll. The results suggest that NH4+-loaded biochar provides environmental benefits by enabling nitrogen recovery from wastewater and demonstrating potential for use as a substrate in seedling development.